'02 Saturn SC, 64K miles, automatic. For about the past week or so, whenever I accelerate, the car accelerates slower than usual, and the RPM needle jumps up. When I finally get up to speed, it's okay. It's just when I've been stopped at a traffic light or whatever. My dad thought it might be the transmission. We took it to the shop last week and they couldn't find anything wrong with it. They changed the transmission fluid and a filter, but it's still not working right. Any ideas?